The Furies also called Erinyes or Eumenidies personified the vengeful moods of the Triple Goddess Demeter, who also called Erinys and punishes the sinners. The Erinys were three in number but their name means the spirit of anger and revenge. They were spoken of in the singular and represented the Scolding Mother. They were especially active whenever a mother was insulted, injured, or even murdered. "Like bitches they pursued all who had flouted blood-kinship and the deference due to it."
Greeks believed the blood of the slain mother infected her murderer with a dreaded spiritual-poison, miasma, the Mother's Curse. This drew the implacable Furies to their victims, and also infected anyone daring to assist the murderer. In fear of attracting the Furies' attention, least they assisted in matricide, people called the Furies Good Ones" (Eumenides) hoping to divert their wrath.
With the emergence of a patriarchical society the Furies began to be called derogatory names such as Daughters of the Eternal Night, Daughters of Earth and Shadow, and also given such character traits as Retaliation-Destruction, Grudge, and the Unnameable. Some said they were born of the castrated Heavenly Father, Uranus.
Later the Furies became synonymous with "fairies" who were associated with witches because of their ability to lay curses on anyone transgressing their law. Perhaps these so-called "fairies" were witches, persons protecting their rights from the encroaching Christian law. Their modus operandi might have been similar to the Women's Devil Bush society in Africa: if a woman complained to the society that her husband abused her, he soon died of a mysterious dose of poison.
Christianity wasted no time in adopting the Furies who became part of God's penal system in Hell: the dog-faced she-demons known as Furies Who Sow Evil, Accusers or Examiners, and Avengers of Crimes. Their constant duties were to punish sinners.
In Christianity their appearance was grotesques. Appearing on the tympanum of Bourges Cathedral they had large pregnant bellies bearing the full moon's Gorgon face, and pendulous breasts terminating in dogs' heads. By comparison in Greek art, the Furies were stern-faced but beautiful women, bearing torches and scourges, with serpents wreathed in their hair like the Gorgons. A.G.H.
Walker, Barbara G. The Woman's Encyclopedia of Myths and Secrets. New York. HarperCollins. 1983. pp. 327-328